Violet-red azo dye and process of making same.



ivo. 737,967.

UNITED STATES rammed September 1, 1903 PATENT OEEIcE.

FRIEDRICH SCHMIDT, OF HOOHST-ON-THE-MAIN, GERMANY, ASSIGNOR TO EARBVVERKE, VORM. MEISTER, LUCIUS & BRUNING, OF HOOHST-ON- THE-MAIN, GERMANY, A CORPORATION OF GERMANY.

VIOLET-RED AZO DYE AND PROCESS OF MAKING SAME.

gPECIFICATION forming part of Letters Patent N0. 737,967, dated September 1, 1903.

Application filed January 14, 1903. Serial No. 139,063.

To all whom it may concern:

Be it known that I, FRIEDRICH SCHMIDT, Ph. D., a citizen of the Empire of Germany, residing at Hochst-on-the-Main, Germany, have invented certain new and useful Improvements in Azo Dyes and Process of Making the Same, of which the following is a specification.

It is known by German Patents Nos. 66,838 and 07,240 that ortho-oxyazo dyestuffs derived from alpha-naphtholsulfonic acid yield blue to black shades by treatment on wool with chromic acid. It is further known that d yestn fis are obtained which contain the orthooxyazo group twice or four times in the dye stuff moleculea result which lends an increased dyeing power and resistance to the dyestuffs. The latter are derived from orthoamidophenol or from 2:6-dian1idophenol. If it is desired to obtain pure naphthaleneazo dyestuffs of the kind in question, the available ortho-amidonaphtholsulfonic acids are soon exhausted, since the majority of them (the alpha beta derivatives) cannotbe dia-zotized or can be diazotized only with a poor yield.

1 have found that the dia-Zo derivatives of beta alpha amidonaphthol or its sulfonic acids may be produced with acid of beta" naphthylaminsulfonic acids, which contain a sulfonic group in the alpha position. If these acids be diazotized and soda be added, the sulfonic group, which can be easily eliminated from the naphthalene nucleus, is separated and there is produced the naphthalene- 2: l-diazo-oxid (W I I I (Berichzfe,XXVII, 679, 2211; Journal of the Chemical Society 1895, 909.) The naphtha- (N0 specimens.)

To produce a disulfonic acid of the naphthalene-2: l-diazo-oxid Example: 38.3 kilos of beta naphthyl amin-alpha alpha beta trisulfonic acid are transformed with 6.9 kilos of nitrite into the diazo compound in the usual manner. The slightly-yellow solution of the diazo compound is then exactly neutralized with caustic-soda lye or sodium carbonate and an excess of the latter being added.' The yellow color of the solution beeomesforange-red and the exchange of the alpha -sulfonic group for the hydroxyl is completed after some hours. It may be heated to centigrade and even above with out decomposition setting in. 'After some time a solution of fifteen kilos of beta-naphthol in one hundred liters of water and 4.5 kilos of caustic soda is added. The formation of the dyestuff occurs after a few minutes by the originally orange-red solution becoming finally violet. If the combination occurs with heating (about 40 to 50 centigrade,) the solution has assumed after one to two hours a pure blue-violet color. On addition of caustic-soda lye the color turns red, also on being acidified. The dyestuif is salted out and dried. Dyed on wool it yields violet-red, which on being boiled with bichromate becomes blue-black. v 7

Having now described inyinvention, what I claim is 1. The herein described process for the manufacture of a violet red azo dyestufi, yielding,wl1en dyed on wool and subsequently treated with chromic acid, fast-black shades, which consists in diazotizing betaB-naphthylamin-alpha alpha beta -trisulfonic acid, in treating this diazo compound with alkali carbonates, and in combining the naphthalene- 2 1 diazo oxid 5:7 disulfonic acid thus formed with beta-naphthol, substantially as described.

2. As a newproduct the dry dyestufE being a brown-black powder, readily soluble in wa ter with a red color, if the dyestuff is salted out from its solution in an acid, and with a blue color if salted out in an alkaline reac 20 FRIEDRICH SCHMIDT.

Witnesses:

ALFRED BRISBOIS, BERNHARD LEYDECKER. 

